Room heater



Nov 17 1942. H. J. DE N. MccoLLUM ROOM HEATER l Original Filed June 10,1939 2 Sheets-Sheet l www. NWN Qww N NNN M E \www NN MNN N www l M M l lMN u R wm N0v- 17, 1942- H. J. DE N. MccoLLuM 2,302,455

Room HEATER l Original Filed June 10, 1939 I 2 Sheets-Sheet 2--*Pa'tentet Nov. 17, 1942 ROOM HEATER l Henry J. De N. McCollum,Chicago, Ill.

Original application June 10, 1939, Serial No. 278,421. Divided and thisapplication January 4, 1941, Serial N o. 373,093

8 Claims.

. My invention relates generally to room heaters ofthe type commonlyknown as unit heaters, and more particularly to improved electricalcircuits and apparatus for controlling the operation of -room heatershaving a self-contained ini ternal combustion heat generator.

This application is a division o f my copending application Serial No.278,421,v filed June 10,

L In general, theL heater comprises'a combustion chamber, a radiatorreceiving the products of combustion therefrom, a blower, or itsequivalent, to move a combustible mixture of vaporized liquid or gaseousfuel and air and the products of combustion thereof through thecombustion chamber and radiator, an igniter to ignite the combustiblemixture, and a fan to circulate the air to be heated through theradiator in intimate heat exchange relationship therewith. I y

It is an object of my invention to provide an improved room heater whichmay be easily started, which will lcontinue in eiective operationwithout attention, and which has a novel automatic electrical controlcircuit.

A further object of my invention is to provide an internal combustionheater with a novel control and safety mechanism which automaticallyenergizes the igniter, starts the movement of combustible -mixturethrough the combustion chamber, starts the circulation of air throughthe radiator and, after combustion has been established turns off theigniter. l

A further object of my invention is to provide an internal combustionheater with a novel electrical control circuit which reenergizes theigniter if the ame becomes extinguished, and stops the blower and theair circulating fan if the combustible mixture is not ignited within areasonable time, or the flame has been extinguished forv a substantialtime.

A further objectl is to provide an improved room heater which isdependable, safe, economical and effective in use, requiring a minlmumamount of attention to operate, and is economical to manufacture.

Other objects will appear from the following description, referencebeing had to the-accompanying drawings, in which:

Fig. l is a front elevation of the heater and a blower for use inconjunction therewith, with the heater casing, combustion chamber and aportion cf the radiator shown in vertical section;

heater and an improved electrical circuit for use therewith;

Fig. 3 is a diagrammatic representation similar to Fig. 2, but showingan alternative arrangement.l

'Referring to Fig. 1, combustible mixture is supplied to the heater,denoted generally by the numeral I0, from a fuel and air mixing chamberI2. This mixingchamber is provided with a Venturi throat I4, a gas inletmetering orifice I6 and air inlet openings I8, which are protected by ashield 20. Gas and air are drawn'lnto this 'chamber and properly mixedto form a comfbustible mixture which passes through a tube 22 intothecombustion chamber 24, and is there ignited either by the burning gaseswithin the chamber-or by an igniter 26. If it is desired to use a liquidfuel, a simple carburetor is provided with. its outlet connected to thefuel supply line.

Although the igniter may take several forms, I prefer to use a heatingcoil of resistance wire. such as nichrome wire, which is electricallyheated to a point above the flash temperature of the fuel used. f.

From the combustion chamber 24 the hot products of combustion passupwardly through a radiator 28 composed preferably of finned coppertubes and into a header 30. From here the gases are conveyed outside thebuilding through Aan exhaust pipe 32. To promote this flow through thecombustion chamber and radiator, a motor driven centrifugal blower 34 isinterposed in the exhaust pipe and maintains the whole system belowatmospheric pressure. The radiator 28 is thus heated to a hightemperature, and this heat is dissipated intothe room by a fan 36 drivenby an electric motor-38.

A room heater, as described generally above, is very eicient in itsoperation, and a small installation will heat a comparatively largeroom.

Because the entire heat producing portion of the system is sealed andoperates below atmospheric pressure, carbon monoxide and other noxiousgases cannot leak from the heater. 1f a leak should develop at any pointin the apparatus, air from the room will iiow into the heater, and ifthis leak should be suillcient to extinguish the nre, the fuel will beshut off in a manner to be pointed out later.

In the electrical control mechanism shown in Fig.` 2, a primary circuitcomprises a main line switch II4 which may be used to shut 0E the heater-for extended periods, a thermostatically controlled mercury tilt switchof conventional Fig. 2 is a diagrammatic representation of the 55 designI IS which is placed in the room to be heated in a position remote fromthe heater and serves to start and stop the heater whenever necessary tomaintain the room temperature substantially constant, and the primary||8 of a transformer |20. The transformer is designed to giveapproximately seven volts in its secondary |22, inasmuch as thesecondary circuit includes open contact switch which may more safely beutilized at low voltages.

The automatic electrical control circuit depends for its operation upontwo similar thermally responsive switches, one |24 mounted upon thecombustion chamber housing and the other |24' secured to the igniterhousing. Since these two switches are similar, a description of one Willsufllce as a description of both.

The switch |24 comprises a top switch blade |28, a bottom blade |30 anda middle blade |32. Each of these blades is insulated from the others bymeans of insulating strips or blocks |34 and the whole is bound togetherby screws or rivets extending through insulating tubes (not shown) in amanner well known. The top and bottom blades |28 and |30, respectively,are resilient, while the middle blade |32 comprises a temperatureresponsive bimetal strip so arranged that 'its outward end flexesdownwardly toward strip |30 as its temperature rises. Each of thesestrips is provided with one or more contact points at its outward endarranged as follows: a contact point |36 on the lower surface of theupper strip |28, a point |38 normally in contact with point |36 andsupported upon a bracket |40 secured to and in electrical contact withthe outwardend of strip |30, a point |42 on the lower surface of thebimetal strip |32, and a point |44 on strip |30 adapted to cooperatewith point 42, but normally separated therefrom at room temperatures orsomewhat thereabove.

The similar elements of similar switch |24' are,

as follows: top blade |28', lower blade |30', bi-

metal blade |32', insulating spacers |34', top blade contact |36',offset contact |38', offset contact supporting bracket |40', bimetalblade contact |42' and lower blade contact |44.

The temperature responsive switch |24 is mounted upon the combustionchamber housing by means of a metal bracket |48, which serves to conductheat from the housing to the bimetal blade |32. in heat conductingrelation to the igniter housing so that when the igniter 26 is energizedit will heat the bimetal blade |32' and deflect its outward enddownwardly.

In the circuit, as shown in Fig. 2, one end of the transformer secondary|20 is grounded while the other end is electrically connected by aconductor |50 to switch blade |30. This conductor |50 also has a branch|52 leading to switch blade |28'. The top switch blade |28 has aconductor |54 secured thereto leading to the igniter 26, the other sideof which is grounded. A conductor The switch |24 is similarly secured 5|56 connects switch blades |32 and |30', while blade |32' is groundedthrough the motor-of the fan 38 by conductor |58, and through the motorof the blower 34 by means of a branch |60 of the conductor |58.

In operation, the main switch ||4 is closed to ythe fan and blower.

blade I 32' is heated and deflected until contact |42' touches contact44', thus completing a circuit through the transformer secondary |22,line |50 and branch |52, blade |28', contacts |36', and |38', bracket|40', contacts |44 and |42', blade 32' and thence to ground throughlines |58 and fan 38, and through branch |60 and blower 34. Thisenergizes the blower 34 which draws a fuel and air mixture through thesystem, and the fan 38 which blows air over the radiator tubes and fins.

As soon as the fuel and air mixture starts to flow through the system,it is ignited by the igniter 26. The heat thus generated by thecombustion raises the temperature of the bimetal strip |32 and deflectsit downwardly until contacts |42 and |44 touch. 'I'he closing ofcontacts |42 and |44 completes an alternative circuit to the fan 38 andblower 34 through conductor |50, blade |30, contacts |44 and |42,bimetal strip |32, line |56, blade |30', contacts |42 and |44', bimetalblade |32' and lines |58 and |60. On slight additional heating, theadditional deflection of bimetal strip |32 urges blade |30v downwardly,thus separating contacts 36 and |38, and deenergizing the igniter 26.Additional heating of bimetal blade |32' similarly separates contacts|36' and |38.

Though switch |24 may be so. adjusted that contact points |36 and |38separate very soon after contact is made between points |42 and |44, thesimilar switch |24 should be adjusted so that considerable deflection ofblade |30' is necessary before points |36' and |38' separate. This isdone so that the bimetal blade |32 will havetime to heat and completeone alternate circuit to the fan and blower by closing contacts |42 and|44 before the other alternative fan and blower circuit is opened byseparating points |36' and |38'. This delay in the separation of points|36' and |38 may be accomplished by making blade |28' with a slightdownward ilexure, so that because of its resiliency. it will followblade |30' Adownwardly for a short distance before separating therefrom.

With the heater operating as outlined above, should the re becomeextinguished for any reason, .the bimetal blade |32 will cool and allowthe igniter to become re-energized to ignite the fuel. If the fire doesnot become rekindled, then continued cooling of bimetal strip 32separates contacts |42 and |44 and deenergizes the fan and blowermotors, thereby shutting olf the heater system with the exception of theigniter circuit.

` When the system is first started and in succession the igniter isenergized and later the fan and blower are started, if the reshould failto start within a reasonable time, continued heating of bimetal strip|32' by the igniter 26 will open contacts |36' and |38', therebyshutting off This occursbecause the lack of heat in the combustionchamber has resulted in the alternate motor circuit not being completed,inasmuch as points |42 and |44 remain separated at room temperatures.

The alternative circuit shown in Fig. 3 has a temperature responsiveswitch |62 which is similar to switch |24', excepting that it isprovided with an electric heater |64 for its bimetal blade |66. Thisheater is placed in parallel with the igniter and is energized at thesame time as the igniter. The switch |62, therefore, serves the samepurpose as switch |24 and may be used in its place in the controlcircuit shown in Fig. 3, if desired.

Its advantage is that it heats the bimetal blade blade |32';

The other elements of switch |62 are an upper |12, lower blade contact|14, lower blade offset bracket |16, offset contact |18, and bimetalblade contact |80. These elements are similar to the comparable elementsof switch |24' and, therefore, need no further description here.

A second temperature responsivev switch |82 may replace switch |24, and,like switch |24, is in heat conducting relation with the combustionchamber housing. This switch has an upper Ablade |84, a lower blade |86,an intermediate bimetal blade |88, and insulating spacers |90, allsimilar to comparable elements of switch |24. The contact points aredifferently arranged, however, and are as follows: The upper blade |8'4is provided with a contact |92 on its lower surface, which at roomtemperature normally touches a contact |94 on the upper surfaceof thebimetal blade |88. On the lowerfsurface of blade |88 a contact |96secured thereto co-operates with, but at room temperature does nottouch, a fourth contact |98 secured to the upper surface of blade |86. i

The other elements in the circuit are a fan -a branch 2|2 thereof,switch blade |68, contacts |12 and |18, contact bracket |16, blade |10,contacts |14 and |80, blade |66 and conductor 2|4, which is connected tothe fan 200 and blower 202 in parallel. This conductor 2|4 is alsoconnected blade |68, lower blade '|10, upper blade contact the operationof the heater is initiated and that it will continue to operatelautomatically under full control. If, for some reason, the fuel lsupplyshould fail, the fan and blower will be shut off. If the flre shouldbecome extinguished, the

'igniter will be re-energized to start combustion again and if within areasonable time combustion does notA start, the fan and Vblower willbe'deenergized and the fuel supply shut off.

The heater and electrically controlled circuit herein described may beused in connection with the automatic control valve arrangement whichshuts off the lf uel supply to the heater when' the fan is not in.operation, and which is described in my aforementioned co-pendingapplication Serial No. 278,421. If this automatic control valve is used,fuel will not be supplied to the combustion chamber until the igniterhas reached a temperature high enough to ignite the fuel and the fanhas-started. If the fan motor should stop, the -fuel supply will bediscontinued and dangerous overheating of the heater prevented.

While I have shown and described a particular embodiment of myinvention, it will be readily apparent to those skilled in the art thatnumerous variations may be made therefrom without departing from thebasic principlesof the construction disclosed. I, therefore, desire toinclude in the following claims all such modifications and variations aswill be readily apparent to those skilled in the art, and by whichsubstantially the 200, a blower 202, an igniter 204, and a transresultsof my invention may be attained in sub 'stantially the same way.

I claim: f 1. In an electrically controlled internal combustion heaterhaving a fuel supply, a combustion chamber, an electrically heatedigniter therein, and a radiator receiving the products of combus- ,tiontherefrom, the combination comprising a source of current supply, amanually operable switch for connecting and disconnecting said source ofcurrent supply, an electrically operated fan for circulating air pastsaid radiator, an electrically operated'blower'for removing the productsof combustion therefrom, an igniter circuit for supplying current tosaid igniter from said source two alternate circuits for supplying curtoswitch blade |86so that after combustion starts and blower to provideenergization vof these units after contacts |12 and |18 have becomeseparated by continued heatingv of the bimetal strip |66. This alternatecircuit consists of the transformer secondary 206, conductor 208, blade|88, contacts |96 and |98, blade |86, and conductor 2|4, which, as hasbeen explained, is connected to the fan 200 and blower 202.

As the bimetal blade |88 is heated and deflects to complete thealternative fan and blower circuit mentioned above, it separates thecontact points |92 and |94 and deenergizes the igniter 204 and bimetalblade heater |64. Y

It will be appreciated that the circuit of Fig. 3

operates to accomplish the same control effectsr is switch |24' of Fig.2.

From the above description of my heater, it is seen that by closing asingle electrical contact,

rent from said source to said fanV and blower, a

thermostatic switch inthe first of said 'alternate' circuits to closesaid 'circuit and supply current to said fan and blower upon the heatingof saidv ture of said combustion chamber to close thesecond of saidalternate circuits to supply current to said fan and blower and to opensaid igniter circuit and discontinue the heating of said igniter uponthe burning of fuel in said combustion chamber, said thermostaticswitches being so adjusted that the second of said alternate circuits isclosed before the first of said circuits is opened.

2. In an electrically controlled internal combustion heater having afuel supply, a combustion chamber and a radiator, thecombination ofa-source of current supply, a manually operable switch for connectingand disconnecting said source of current supply, an electricallyoperated fany for circulating air past said radiator, an electricallyoperated blower for removing the products of combustion therefrom, twoalternate electrical circuits for supplying current to said fan andblower from said source of supply, an igniter circuit for supplyingcurrent to said igniter from said source of supply, a bimetallicthermostatic switch responsive to the temperature of said igniter toopen said circuit at room` temperatures, to close said circuit upon themoderate heating of said igniter, and to open said circuit upon thefurther heating of said igniter, a second bi-metallic thermostaticswitch responsive to the temperature of said combustion chamber to closethe second of said alternate circuits upon the burning of fuel in saidheater, and means to open said igniter circuit upon said burning offuel, said bi-metallic switches being adjusted to close said secondalternate circuit before opening said first circuit.

3. In an electrically operated internal combustion heater having a fuelsupply, a combustion chamber, and a radiator for receiving the productsof combustion therefrom, the combination of a source of current supply,a manually operable switch for connecting and disconnecting said sourceof supply, an electrically heated igniter in said combustion chamber, anigniter circuit for supplying current to said igniter from said sourceof supply, an electrically operated fan for circulating air past saidradiator, an electrically operated blower for removing the products ofcombustion therefrom, two alternate circuits for energizing said fan andblower from said source of supply, a thermostatic switch in the first ofsaid alternate circuits responsive to the temperature of an electricswitch heater to close said circuit and energize said fan and blowerupon the heating of said igniter and to open said rst circuit upon thecontinued heating of said switch by the heater, an electric switchheater in said igniter circuit to heat said thermostatic switch whencurrent is passed through said igniter, and a second thermostatic switchresponsive to the temperature of said heater to close the second of saidalternate circuits upon the burning of fuel in said combustion chamber,said thermostaticI switches being adjusted to provide a continuoussupply of current to said fan and blower during the time that combustionoccurs in said combustion chamber.

4. In an electrically controlled internal combustion heater having afuel supply, a combustion chamber, a radiator, a source of currentsupply, and a manually operable switch to connect and disconnect saidsource of current supply, the combination comprising an electricallyheated igniter in said combustion chamber, an electrically operated fanfor circulating air past said radiator, anvelectrically operated blowerto cause the circulation of products of combustion therethrough, anelectrical circuit connected to said source of supply for energizingsaid fan and blower, a thermostatic switch in said circuit, open at roomtemperatures and operable upon the heating of said igniter to close saidcircuit and energize said fan'and blower, and upon further heating toopen said circuit, a second circuit connected to said source of supply,and a thermostatic switch 'in said second circuit and responsive to thetemperature of said heater to energize said fan and blower upon theburning of fuel in said combustion chamber, said thermostatic switchesbeing adjusted to provide a continuous supply of current to said yfanand blower during the combustion of fuel in said heater.

5. In an electrically controlled internal cornbustion heater having afuel supply, a combustion chamber, anda radiator receiving the productsof combustion therefrom, the combination comprising a source of electriccurrent supply,

a manually operable switch for connecting and disconnecting said sourceof current supply, an igniter, anvelectrically operated fan forcirculating air past said radiator, an electrically operated blower forremoving the products of combustion therefrom, two alternate electriccircuits for energizing said fan and blower, a thermostatic switch inthe first of said circuits responsive to the temperature of said igniterto open said circuit at room temperatures,l to close said circuit uponmoderate heating of said igniter, and to open said circuit uponcontinued heating of said igniter, a secondl thermostatic switchresponsive to the temperature of said heater in the second of saidalternate circuits to energize said fan and blower upon the burning offuel in said combustion chamber, said thermostatic switches beingadjusted to supply current continuously to said fan and blower whencombustion occurs in said heater.

6. In an electrically controlled internal combustion heater having afuel suply, a combustion chamber, and a radiator receiving' the productsof combustion therefrom,- the combination of a source of electriccurrent supply, a manually opv erable switch for connecting anddisconnecting said source of supply, an electrically heated igniter insaid combustion chamber, an igniter circuit for supplying current tosaid igniter from f said source of supply, an electric switch heater insaid igniter circuit, an electrically energized motorcircuit foroperating said heater, two al ternate circuits for energizing said motorcircuit from said source of supply, a thermostatic switch in the firstof said alternatecircuits responsive to the temperature of said electricswitch heater to open said circuit at room temperatures, to close saidcircuit upon moderate heating of said igniter, and to open said circuitupon continued heating of said igniter, and a second thermostatic switchresponsive to the temperature of said heater in the second of saidalternate circuits, to open said second circuit at room temperatures, toclose said second circuit upon a rise in heater temperature caused bycombustion of fuel in said combustion chamber, to open said ignitercircuit when said combustion has been established, and to close saidigniter circuit at temperatures below those produced by combustion, saidthermostatic switches being adjusted to provide an uninterupted supplyof current to said fan and blower during the time that combustion occursin said combustion chamber.

7. In an' electrically controlled internal combustion heater having afuel supply, a combustion chamber and a radiator receiving the productsof combustion therefrom, the combination comprising a source of electriccurrent supply, a manually operable switch for connecting anddisconnecting said source of supply, an electrically heated igniter' insaid combustion chamber, an igniter circuit for supplying current tosaid igniter from said source of supply, an electrically energized motorcircuit for operating said heater, two alternate circuits for energizingsaid motor circuit from said source of supply, a thermostatic switch inthe rst of said alternate cir-v cuits, open at room temperatures andoperative as said igniter is heated to close said tlrst circuit andenergize said motor circuit, and upon further heating of said igniter toopen said circuit, and a thermostatic switch in the second of saidalternate circuits, responsive to the temperature of said heater toclose said second circuit and energize said motor circuit whencombustion is established in said combustion chamber, said temperaturesand operative as said igniter is 'thermostatic switches being adjustedto provide a heated to close said first circuit and energize saidcontinuous supply of current to said motor cir. motor circuit, and uponfurther heating of said static switch in said first circuit, open atroom cuit during the combustion o! fuel in said heater. Y igniter toopen said circuit, a second circuit for 8. In an electrically operatedinternal combusenergizing said igniter and said motor circuit tionheater having a fuel supply, a combustion from said source of supply anda thermostatic chamber and a radiator receiving the products of switchin said second circuit responsive to the combustion therefrom, thecombination compristemperature of said heater, and operative at ing asource of electric current supply, a manu-- room temperatures toenergize said igniter cirally operable switch for connecting and discon-10 cuit and upon a rise in 'temperature caused by necting said source ofsupply, an electrically enthe burning of fuel in said heater todiscontinue ergized motor circuit for operating said heater, v theenergization of said igniter circuit and to an electrically heatedigniter in said combustion energize said motor circuit, saidtherrnostatic chamber, an igniter circuit for supplying current switchesbeing adjusted to provide a continuous to said igniter, a rst circuit toenergize said mo- 15 supply ofA current to said motor circuit during torcircuit from said source of supply, a thermooperation of said heater.

HENRY J. DE N. MCCOLLUM.l

